mips: ralink: rt288x: introduce 'soc_device' initialization

RT288X SoCs have their own 'ralink_soc_info' structure with some
information about the soc itself. In order to be able to retrieve this
information from driver code and avoid architecture dependencies for
retrieving these details introduce this 'soc_device'. Set 'data' pointer
points to the struct 'ralink_soc_info' to be able to export also current
soc information using this mechanism. We need to select 'SOC_BUS' in
Kconfig configuration for these SoCs.

Signed-off-by: Sergio Paracuellos <sergio.paracuellos@gmail.com>
Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>

arch/mips/ralink/Kconfig

@@ -29,6 +29,7 @@ choice
 		select MIPS_AUTO_PFN_OFFSET
 		select MIPS_L1_CACHE_SHIFT_4
 		select HAVE_PCI
+		select SOC_BUS
 
 	config SOC_RT305X
 		bool "RT305x"

arch/mips/ralink/rt288x.c

@@ -10,6 +10,8 @@
 
 #include <linux/kernel.h>
 #include <linux/init.h>
+#include <linux/slab.h>
+#include <linux/sys_soc.h>
 
 #include <asm/mipsregs.h>
 #include <asm/mach-ralink/ralink_regs.h>
@@ -17,6 +19,8 @@
 
 #include "common.h"
 
+static struct ralink_soc_info *soc_info_ptr;
+
 void __init ralink_clk_init(void)
 {
 	unsigned long cpu_rate, wmac_rate = 40000000;
@@ -98,6 +102,31 @@ static unsigned int __init rt2880_get_soc_rev(void)
 {
 	return (rt2880_get_soc_id() & CHIP_ID_REV_MASK);
 }
+
+static int __init rt2880_soc_dev_init(void)
+{
+	struct soc_device *soc_dev;
+	struct soc_device_attribute *soc_dev_attr;
+
+	soc_dev_attr = kzalloc(sizeof(*soc_dev_attr), GFP_KERNEL);
+	if (!soc_dev_attr)
+		return -ENOMEM;
+
+	soc_dev_attr->family = "Ralink";
+	soc_dev_attr->soc_id = rt2880_get_soc_name();
+
+	soc_dev_attr->data = soc_info_ptr;
+
+	soc_dev = soc_device_register(soc_dev_attr);
+	if (IS_ERR(soc_dev)) {
+		kfree(soc_dev_attr);
+		return PTR_ERR(soc_dev);
+	}
+
+	return 0;
+}
+device_initcall(rt2880_soc_dev_init);
+
 void __init prom_soc_init(struct ralink_soc_info *soc_info)
 {
 	if (rt2880_soc_valid())
@@ -117,4 +146,5 @@ void __init prom_soc_init(struct ralink_soc_info *soc_info)
 	soc_info->mem_size_max = RT2880_MEM_SIZE_MAX;
 
 	ralink_soc = RT2880_SOC;
+	soc_info_ptr = soc_info;
 }